Process for coloring textile materials



Patented Mar. 27, 1951 UNITED STATES PATENT orrics PROCESS FOR COLORING TEXTILE MATERIALS Charles E. Maher, Chicago, Ill.

No Drawing. Application November 26, 1948, Serial No. 62,229

This invention relates to a commercial textile mill process for the permanent coloration of textile materials.

More specifically, this invention relates to a commercial textile mill process for the permanent coloration of textile materials or textile fabrics including both acetate rayon and viscose rayon, and nylon, as well as cotton and so-called union, mixed, or combination fabrics, such as those composed of cotton and viscose rayon, or those composed of acetate rayon and viscose rayon, employing a diazotizable azo base dyestuff and phloroglucinol (1,3,5-trihydroxybenzone) as a coupling agent, or developer, as distinguished from efforts heretofore made to use phloroglucinol and analogous phenolic coupling agents in the synthesis or manufacture of diazotizable azo base dyestuffs, per se.

While I am aware of the fact that processes have been devised heretofore for using various phenolic compounds such, for example, as resorcinol, pyrogallol, and phloroglucinol, as coupling agents in the synthesis or manufacture of azo dyestuffs, per se, no satisfactory process has been known heretofore, insofar as I am aware, for utilizing phloroglucinol as a coupling agent with diazotizable azo base dyestuffs in a commercial textile mill process for the permanent coloration of textile materials so as to produce or form permanent colors or pigments on any and all of the textile fabrics of the character hereinbefore referred to including both acetate rayon and viscose rayon, nylon, cotton, and socalled union, mixed, or combination fabrics, such as those composed of cotton and viscose rayon, and those composed of acetate rayon and viscose rayon. 7

Moreover, the conditions under which phloroglucinol or analogous phenolic materials, such as resorcinol and pyrogallol, may be employed as coupling agents in the synthesis or manufacture of azo dyestuffs, per se, are entirely dissimilar to and unrelated to the conditions under which the present process for the permanent coloration of textile materials is carried out as a commercial textile mill process, and which necessitates careful control of both the diazotizing bath and the coupling bath and other carefully controlled conditions which must be especially adapted to the particular textile fabric upon which the de-- sired permanent color or pigment is being formed, as will be pointed out hereinafter.

The most commonly used coupling agent here} tofore employed in coupling diaz'otized azo base dyestuffs to textile fabrics has been betao'xynaphthoic acid (German Bona) which will function effectively as a coupling agent in a coupling bath containing free nitreous acid (HNOz) carried over into the coupling bath from the'diazotizing bath. However, phlorogluoinol (1,3,5-trihydroxybenzene) will not function as a coupling agent in the presence of free nitrous acid carried over into the coupling bath from the diazotizing bath (in which an excess of free nitrous acid is harmless); Moreover, unlike laboratory operation where effective hand rinsing of specimens is readily and effectively accomplished, it is difficult in commercial textile mill practice to rinse the textile material sufficiently to eliminate such an excess of free nitrous acid from the textile material after it has been removed from the diazotizing bath and before it enters the coupling bath. Moreover, such a rinsing operation is uncertain in the results obtained thereby. Likewise, it has been found not to be practical to attempt to eliminatefree nitrous acid in the coupling bath by adding thereto a strong alkali such as caustic soda, caustic potash, soda ash, (sodium carbonate) or the like, for reasons which will be pointed out hereinafter. v

The effect of free nitrous acid upon phloroglucinol, or 1,3,5-trihydroxybenzene, in a coupling bath is that the free nitrous acid tends to decompose and to form free nitroso (NO) groups which attach themselves to the unsaturated free bonds or valences in the phloroglucinol molecule,

in this manner:

no on alkaline material to the coupling bath, in a quantity sufficient to neutralize the free nitrous acid and therein tends to raise the pH of the coupling bath to a point where it is above 7.0 and hence alkaline. lhis renders it impossible to use phloroglucinol for coupling diazotized azo base dyestuffs on acetate rayons and nylon since pholoroglucinol couples with difhculty to such diazotized acetate rayons and nylon in an alkaline medium.

Moreover, the only coupling agent or developer which has been known and used heretofore for coupling diazotizable azo base dyestuffs to acetate rayon and nylon fabrics, namely, betaoxynaphthoic acid, (German Bona), cannot be used as a coupling agent or developer for diazotizable azo base dyestuffs in dyeing mixed or so-called combination fabrics composed of cotton or viscose rayon and either acetate rayon or nylon because viscose rayon and cotton fabrics can be developed only in an alkaline medium and betaoxynaphthoic acid will not develop satisfactory shades of color with cotton or viscose rayon dyes in an alkaline medium.

Furthermore, it has not been customary here-- tofore to diazotize and couple dyestuffs employed for dyeing textile fabrics in brown, in wine color, and in various other colors, because when such diazotizable azo base dyestuffs have been coupled with the most commonly used coupling agent heretofore known for use with diazotizable azo base dyestuffs, namely, betaoxynaphthoic acid, the resulting colors change shade radically upon hot washing. However, in the practice of the present invention textile materials may be dyed with brown diazotizable azo base dyestuffs, wine color diazotizable azo base dyestuffs, or diazotiaable azo base dyestuffs affording various other colors, diazotized and coupled and subjected to repeated hot washing operations, as well as to varying atmospheric and climatic conditions, without loss of wash or light fastness or change of shade.

Accordingly, an object of the present invention is to provide a commercial textile mill process for the permanent coloration of textile materials employing diazotizable azo base dyestuffs and employing phloroglucinol as a developing or coupling agent and which, in use, overcomes the foregoing and other difficulties heretofore experienced in the art.

Another object of the present invention is to provide an eificient commercial textile mill process for forming permanent colors or pigments on synthetic textile fabrics includ ng acetate rayon and nylon, viscose rayon and cotton fabrics, as well as upon so-called union, mixed, or combination fabrics, such as those composed of nylon and viscose rayon, or fabrics composed of acetate rayon and viscose rayon, employing a diazotizable azo base dyestufi and employing phloroglucinol as a coupling agent or developer.

An additional object of the present invention is to provide a novel commercial textile mill process for forming permanent colors or pigments upon textile fabrics, of the character hereinbefore indicated, and which colors or pigments are highly stable and permanent under varying atmospheric conditions, upon exposure to sunlight, and when such colored textile fabrics are subjected to washing and ironing operations in use.

A further object of the present invention is to provide a new and improved commercial mill textile process for coupling diazotizecl azo base dyestuffs or diazonium salts to the various simple and union, mixed, or combination fabrics herein referred to in such a manner that free nitrous acid is eliminated from the coupling bath before the coupling reaction takes place with the result that the diazoniurn salt or salts are able to couple themselves to the free or unsaturated bonds or valences in the phloroglucinol or l,3,5- trihydroxybenzene molecule, and ich the diazcnium salt or salts could not do 11' the free or unsaturated positions in phloroglucinol or 1,3,5-trihydroxybenzene molecule were already occupied by nitroso (NO) groups resulting from the decomposition of the free nitrous acid (HNOz) carried over into the coupling bath from the diazotizing bath.

An additional object of the invention is to provide a new and improved textile process for dyeing textile materials in blue, brown, wine color, and in various other colors employing appropriate diazotizable azo base dyestuffs and employing phlorogiucinol as a coupling agent with the result that textile materials colore in black, blue, brown, wine color, and in various other colors, are obtained which have excellent wash fastness and excellent light fastness under widely varying atmospheric and climatic conditions and which do not exhibit change of shade upon repeated hot washings.

()ther objects will appear hereinafter.

In the practice of the present in ention free nitrous acid (l-iNOz) is eliminated from the coupling bath by the addition thereto of sodium acetate which converts the free nitrous acid into sodium nitrite (NaNOz) or by the addition to the coupling bath of sulfamic acid and urea, or other suitable amine such, for example, melamine. Both of these procedures result in the ination of the free nitrous acid from the coupling bath and prevent the formation of nitroeo (HG) groups which, when present in the coupling bath, tend to attach themselves to the unsaturated bonds or valences in the phloroglucinol cl droxybenzene molecule and thereby prevent the diazonium salt from being coupled thereto during the coupling operation.

This procedure overcomes the difficulties tofore experienced in the art including the pi. tical difiiculties involved in attempting to 8111311 nate free nitrous acid from the textile material or fabric by the uncertain operation of rinsing the textile material or fabric after it has been ra'mcved from the diazotizing prior to the time it is worked in the coupling bath. Such rinsing operations are unsatisfactory and the results are highly variable since in commercial tex tile mill practice it is difficult to rinse extile terials sufficiently after they leave the diazotizing bath to assure that all free nitrous acid is elimi nated therefrom. Hence it will be appreciated that the problem of rinsing textile materials aiter they are withdrawn from the diazotizing bath, to eliminate free nitrous acid therefrom, is not comparable to hand rinsing specimens of textile materials in laboratory practice where efficient rinsing is readily accomplished.

It is believed, in this connection, that the NH; or amino groups the sulfarnic and urea, or in the melamine or other suitable amine, absorb the free nitrous acid in-the cou g bath and thus prevent the formation of nitiosc (NO) groups and their attachment to th. nsaturated bonds or valences in the phloroglu trihydroxybenzene molecule, ed out A suitable procedure which may be followed in the practice of the present invention in permanent black colors or pigments upon textile materials or fabrics composed entirely of cellulose acetate rayon, and as a commercial textile mill process, is illustrated in the following example:

EXAMPLE 1 (a) Dyeing procedure To dye 100 p unds of cellulose acetate rayon (100 per cent), 5 pounds of acetate rayon diazo black dyestuff, namely, para-amino-benzene-azorial may be withdrawn from the dye bath and rinsed in cold water.

(1)) Diaz'o'iz'aing procedure 7 The cellulose acetate rayon fabric which has been subjected to the dyeing procedure, as in step (a) above, may then be immersed in a bath having a temperature not in excess of 80 F. and containing 5 pounds of sodium nitrite (NaNOv and 10 pounds of commercial hydrochloric acid (H01) (22 Be.) in from to 400 gallons of water depending upon the type of machine employed, and other variable factors, and the cellulose acetate rayon fabric may be worked in this diazotizing bath for a period of one-half hour, after which the textile material or fabric may be Withdrawn from the diazotizing bath and rinsed in cold water.

(0) Coupling procedure The coupling bath may be prepared by adding 2 pounds of sodium acetate (CHaCOO-Na), 2 pounds of sulf-amic acid, and 8 ounces of phloroglucinol (1,3,5-trihydroxybenzene) to from 100 to 400 gallons of water maintained at a temperature not in excess of 96 F. The pH of the coupling bath may be adjusted by means of a weal; alkali or a Weak alkaline salt, such as the sodium acetate specified above, or by means of a weal; acid, such as acetic acid, until it is within the critical limits of 5.0 and 7.0. The cellulose acetate rayon fabric, diazotized as in the foregoing step (b), may then be immersed in the coupling bath for a period of approximately 15 minutes. The temperature of the coupling bath may then be raised, during a period of 20 minutes, to a tem perature of from F. to whereupon the acetate rayon fabric may be run in the coupling' bath at this temperature for an added period of 30 minutes to complete the coupling operation. The thus dyed, diazotized, and coupled or developed cellulose acetate rayon fabric may then be rinsed in cool water and finished in the usual manner.

In place of the 2 pounds of suliamic acid referred to above, 2 pounds of urea may be employed with 2 pounds of sodium acetate, in this example, or, if desired, mixtures of sodium acetate, sulfamic acid, and urea, or melamine, or

other suitable amine, may be employed to eliminate any free nitrous acid (HNOz) which may be carried over into the coupling bath from the diazotizing bath with the resulting objectionable formation of nitroso (NO) groups which would 6 tend to attach themselves to the unsaturated positions on the phloroglucinol or 1,3,5-trihydroxybenzene molecule and thus prevent the diazonium salt from being coupled thereto during the coupling operation, while employing sodium acetate, or a mixture of acetic acid and soda ash, to control the pH of the coupling bath, as indicated.

Thus, in the present example, Lmay employ 2 pounds of sodium acetate, 1 pound of sulfamic acid, and 2 pounds of urea, or melamine, or other suitable amine, in place of the 2 pounds of sodium acetate and the 2 pounds of sulfamic acid specified.

In the practice of the present invention, as set forth in the foregoing Example 1, the sodium acetate, the sulfamic acid and the urea, or melamine, 01' other suitable amine, cooperate to neutralize in the coupling bath, prior to the coupling operation therein, any residual or free nitrous acid which may have been carried over into the coupling bath from the diazotizingbath, as eX- plained above. The mechanism by which the sodium acetate, the sulfamic acid and the urea, or melamine, or other suitable amine, cooperate to neutralize any free or residual nitrous acid which may have been carried over into the coupling bath from the diazetizing bath is, of course, in the case of the sodium acetate, by the formation of sodium nitrite and, in the case of sulfamic acid and urea, or melamine, or other suitable amine, by combining with the nitroso (NO) groups, which are formed by the presence of free or residual nitrous acid in the coupling bath, to form an inert material. In this manner substantially ail free nitrous acid is eliminated from the coupling bath and the formation of nitroso (NO) groups which otherwise would be formed and would combine with the free or unsaturated bonds or valences in the highly reactive phloroglucinol or 1,3,5trihydroxybenzene molecule is prevented and the free bonds or positions in the phloroglucinol molecule are thus left free to combine with the diazonium salt of the diazotized azo base (black) dyestuff during the coupling operation.

While sodium acetate may be employed without the use of sulfamic acid or other amine for the purpose of neutralizing any free or residual nitrous acid in the coupling bath, by employing somewhat larger quantity of sodium acetate than that specified in the foregoing Example 1, it has been found advantageous to employ sodium ace-.

tate and sulfaniic acid in combination since when so used the two materials effectively cooperate more positively to eliminate any residual or free nitrous acid which may be present in the coupling bath and which, if not eliminated, would interfere with the coupling operation therein.

By maintaining the pH of the coupling bath between the critical limits of 5.6 and 7.0, as set forth in the foregoing Example 1,'by means of sodium acetate, the free acetic acid present in the coupling bath is sufficiently bufiered to prevent the formation of any free nitrous acid therein.

In place of the sodium acetate which is specified in the foregoing Example 1 for controlling the pH of the coupling bath, I may employ equivalent amounts of any of the following materials or mixtures thereof, namely, sodiumj formats, borax, boric acid, soda ash, or any other mild alkaline or acid material in a controlled quantity, care being exercised to avoid an excess thereof.

The cellulose acetate rayon fabric thus treated, according to the foregoing Example 1, has a permanent true black color or pigment which is highly resistant to the action of sunlight and varying atmospheric conditions while also being highly resistant to the action of washing and ironing.

EXAMPLE 2 followed in o o 113 o Hi mnOOnm 41101 2NaNO Dianisidinc 0 CH3 0 c Hi Diazonium salt of dianisidinc (pale pink in color) The reaction involved in coupling the diazonium salt of dianisidine upon cellulose acetate rayon, employing phloroglucinol as a coupling agent, may be illustrated as follows:

OCHg 00113 Diasonium salt of dianisidine OH Phloroglucinol 0 CH 0 CH OH I I OH HO OH OH H0 The resulting color or pigment thus obtained will be a true black if a sufficient quantity of the dianisidine salt is employed but may shade to deep navy blue if a smaller proportion of the dianisidine salt is employed.

Instead of coupling in only one position on the phioroglucinol molecule, as in the foregoing reaction, the diazonium salt of dianisidine may couple with the phloroglucihol molecule in either 2 or 3 places on the phloroglucinol molecule, each in meta position to each other, as indicated above.

Other diazotizable aao base dyestufis which may be employed in place of dianisidine, in the practice of the present invention, in dyeing cellulose acetate rayon fabrics, are the following: tolidine, orthotolidine, para-amino-di-phenylamine, p-p-ar'iino diphenylamine, para-aminobenzene azo-naphthylamine, and amino-a20- benzene.

A suitable procedure which may be followed in the practice of the present invention in forming permanent black colors or pigments on a so-called union, mixed, or combination fabric composed of 50 per cent cellulose acetate rayon and 50 per cent viscose or regenerated cellulose rayon, or upon a union, mixed, or combination fabric composed of cellulose acetate rayon and cotton, is illustrated in the following example:

EXAMPLE 3 To dye pounds of the fabric 2.5 pounds of acetate rayon diazo black dyestuff, namely, paraamino-benzene-azo-dihydroxyethylanilin, may be formed into a paste with hot water and a Wetting agent such, for example, as a diethanolamine fatty acid condensate. 4 pounds of viscose rayon or cotton diazo black dyestuff, namely, Color Index Dyestuff No. 401, which is the sodium salt of diphenyl diazo 3 sulpho-7-amino-i naphthol-S amino-1 naphthol 3.6 disulphonic acid, is then added to the dyeloath While the latter is maintained at a temperature of F. 100 pounds of a so-called union, mixed, or combination fabric composed of 50 per cent cellulose acetate rayon and 50 per cent viscose or regenerated cellulose rayon, or 100 pounds of a mixed fabric composed of 50 per cent cellulose acetate rayon and 50 per cent cotton, which has been previously Well scoured, may then be immersed and worked in the dyebath thus prepared for a period of 15 minutes during which time the temperature of the dyebath is raised to 185 after which the fabric is worked in the dyebath for an additional 20 minutes. 30 pounds of common salt (NaCl) may then be added to the dyebath and the fabric worked therein for an additional 45 minutes, after which the thus treated union, mixed, or combination fabric may be rinsed in cold water and diazotized as in step 2) of the foregoing Example 1. The thus dyed and diazotized selected cellulose acetate rayon-viscose rayon fabric, or a selected cellulose acetate-cotton. fabric, may then be rinsed in cold Water and developed or coupled as follows:

The coupling bath may be prepared by dissolving either pounds of sodium acetate alone, or by the use of a mixture of 1.5 pounds of sulfamic acid with 1.5 pounds of acetate, in from 100 to 400 gallons of water, depending upon the type of apparatus employed, at a temperature not in excess of 76 F., to which may be added 8 ounces of phloroglucinol. The dyed and di azotized so-called unio mixed, or combination fabric may then be introduced into the cold coupling or developing bath and worked therein for 25 minutes, whereupon the coupling or developing bath may be heated to a temperature of F. and the fabric worked in the coupling or developing bath at this temperature for an additional period of 25 minutes. The thus dyed, diazotizecl and coupled fabric may then be removed from the coupling bath and rinsed and finished as usual.

During this process of diazotizing and coupling a so-called union, mixed, or combination fabric, such as cellulose acetate rayon and viscose rayon, or acetate rayon and cotton, the coupling bath is maintained at room temperature or lower (not over 75 F.) and at a pH of 7.0 for a period of 20 minutes, to enable the selected viscose rayon or cotton diazo black dyestuif to be coupled to the phloroglucinol, after which the pH of the coupling bath should be lowered to a point below LG and the temperature raised to 140 F. and maintained at this temperature for a period of 30 minutes, so as to enable the acetate rayon dyestuif in the so-called union, mixed, or combination fabric to be coupled to the phloroglucinol on the acid side, 7

A suitable procedure which may be followed, in the practice of the present invention, in dyeing nylon fabrics, is illustrated in the following example EXAMPLE 4 (a) Dyeing pnocedure To dye o pounds of nylon fabric, 7 pounds of 'di'azo black. dyestuff, namely, para-amino-ben- -zene-azo-dihydroxyethylanilin, may be worked into a paste with hot water and then dispersed in from 100 to 400 gallons of water to form the dye bath. 100 pounds of nylon fabric, which has been thoroughly scoured, may then be immersed in the dye bath and the dye solution worked through the nylon fabric for a period of from 1 to 2 hours while maintaining the dye bath at a temperature of 200 F.

(b) Dia'aotizing procedure The thus treated nylon fabric may then be immersed in and worked for a period of approximately one-half hour in a diazotizing bath containing 16 pounds of concentrated sulphuric acid (H2SO4) and 16 pounds of sodium nitrite (NaNoz) dissolved in from 100 to 400 gallons of Water, While maintaining the diazotizing bath at a temperature not in excess of 89 F.

(c) Coupling procedure The coupling bath for the thus dyed and di-- azotized nylon fabric may be prepared by dissolving 2 pounds of sodium acetate (CHBCOONa), 2 pounds of sulfamic acid, and 12 ounces of phloroglucinol in from 100 to 400 gallons of water, maintained at a temperature not in excess of 90 F. The pH of the coupling bath may be adjusted by means of a weak salt, such as sodium acetate, or by means of a weak acid, such as acetic acid, as may be necessary, until it is within the critical limits of 5.0 and 7.0. The nylon fabric, diazotized as in step (b) above, may then be immersed in the coupling bath for a period of approximately 15 minutes. The temperature of the coupling bath may then be raised,

during a period of minutes, to a temperature has good light and wash fastness.

Other suitable diazotizable azo base black dyestuffs which may be employed in dyeing nylon fabric, according to the practice of the present invention, as set forth in the foregoing Example 4, and in place of the diazotizable azo base dyestuif therein referred to, are para-aminobenzene-azo-naphthylamine and para-aminodiphenylamine.

A suitable procedure which may be followed, in the practice of the present invention, in dyeing, diazotizing and coupling a diazotizable azo base black dyestuif on a so-called uniommixed or combination fabric composed-of, for example, either 50 per cent wool or 50 per cent silk and 50 per cent acetate rayon is illustrated in the following Example 5:

Example 5 To dye 100 pounds of a so-called union, mixed or combination fabric composed of either 50 per cent wool or 50 per cent silk and 50 per cent acetate rayon the dye bath and the diazotizing bath may be prepared, and the dyeing and diazo'tizing operations carried out, in the same manner set forth in the foregoing Example 1 in reference to dyeing and diazotizing a fabric which is composed entirely of cellulose acetate rayon. The thus dyed and diazotized union, mixed or combination fabric may then be immersed in a' coupling bath prepared by dissolving -2 pounds of sodium acetate and 8 ounces of phloroglucinol in from to40il gallons of water, depending upon the type of apparatus employed, the pH of the coupling bath being adjustedto 6.5. The fabric is worked in the coupling bath at room temperature for a period of 15 minutes, the temperature of the coupling bath is then raised to F., and the fabric worked for an additional 20 min-' utes in the coupling bath, at this temperature. 4' pounds of acid black or chrome black may then be added to the coupling bath and the so-called union, mixed or combination fabric may then be subjected to the usual procedure for dyeing wool or silk, namely, by adding to the coupling bath 3 pounds of acetic acid and 20 pounds of'Glaubers salt (NazSOi), raising the temperature of he dye bath thus prepared to F., and then working the so-called union, mixed or combination fabric (composed of either 50 per cent wool or 50 per cent silk and 50 per cent acetate rayon) in the dye bath at this temperature for 30 minutes or untilthe wool or silk component of the fabric is dyed to the same shade as the previously dyed, diazotized and coupled acetate rayon component of the'fabric, whereupon the fabric may be removed from the dye bath and rinsed and finished as usual. I

A typical acid black which may be employed in the practice of the present invention, as set forthin the present Example 5, is the sodium salt of p nitrobenzene azo 3:6 disulpho lamino-8-naphthol-azo-benzene, and a suitable chrome black which may be employed in place thereof is either the sodium or the zinc salt of 4 supho-Z-hydroxy a naphtholene azo B- naphthol.

While the present invention has thus far been described as being applicable to the coloring of textile materials in black colors, and is particu larly adapted and intended for such usage, the invention is not limited thereto since the invention is also applicable to the coloring of textile materials in various other colors including blue, red, tan, yellow, and brown and various shades thereof. I

While it is theoretically possible, within the scope and contemplation of the present invention to eliminate substantially all free nitrous acid from the coupling bath by proper processing and adequate rinsing of the textile material after the diazotizing operation, the procedure hereinbefore set forth for accomplishing this result is preferred since it is more positive than rinsing and is a positive safeguard against improper processing and inadequate rinsing.

It will thus be seen from the foregoing description that the present invention ((1) provides a new and improved method of coupling diazotized azo base dyestuffs to fabrics which are composed entirely of cellulose acetate rayon, so-called union, mixed, or combination fabrics composed inpart of cellulose acetate rayon and in partof viscose orregenerated cellulose rayon, so-called union, mixed, or combination fabrics composed in part of cellulose acetate rayon and in part of cotton, fabrics composed of nylon, and so-called union, mixed, or combination fabrics composed in part of natural silk and in part of acetate rayon; (Z2) thatv the present invention provides a novel and efficient method for eliminating freenitrous with its at-- tendant difficulties, hereinbefore pointed out, from the coupling bath; and. (c)- that the present invention overcomes. the shortcomings of the coupling agent most commonly used heretofore, namely, betaoxynaphthoic acid (German Bona), as a coupling agent for diazotized azo base dyestufis particularly in that betaoxynaphthoicacid can not be used as a coupling agent for diazotizable azo base dyestuffs in dyeing mixed or so-called union or combination fabrics composed of cotton or viscose rayon and either acetate rayon or nylon because viscose rayon and cotton fabrics can be developed only in an alkaline medium and betaoxynaphthoic acid will not develop satisfactory shades of colors with cotton or viscose rayon dyes in an alkaline medium.

It will thus also be seen from the foregoing description that the present invention provides a novel and efiicient commercial textile process for forming permanent black colors or pigments of excellent wash and light fastness upon the simple and mixed or combination textile fabrics hereinbefore referred to, and thatjthe invention thus. has the desirable advantages and characteristics, and accomplishes its intended objects, including those hereinbefore pointed out andothers which are inherent in the invention.

1' claim:

1. A process for forming permanent and true black colors or pigments, possessing excellent wash fastness and light fastness, upon hydrophobic textile materials, which comprises forming a coupling bath containing phloroglucinol (=l,3',5 trihydroxybenzene) as the coupling agent, dyeing the hydrophobic textile material with a selected diazoti'zable azobase black dyestuff present in the ratio of at least 3" mols of the black dycstufl per mol of phloroglucinol, working the thus dyed hydrophobic textile material in a diazolizing bath to form the diazonium salt of the selected diazotizable arc base black dyestufl, eliminating from the coupling bath prior to the coupling operation therein any free nitrous acid which may be present in the coupling bath; and then working the thus dyed and diazotized hydrophobic textile material in the said coupling bath to complete the coupling operation therein.

2. The process definedin claim 1 in which the hydrophobic textile material is cellulose acetate rayon and in which the diazotizable azc base dyestuff employed is a diazotizable azo base acetate black dyestuff.

3-. lhe process defined in claim 1 in which the hydrophobic textile material is nylon and in which the diazotizable azo base dyestuff employed is a di'azotizable azo base nylon black dyestuff.

4. The process definedin claim 1 in which the textile material is a so-called union, mixed, or combination fabric composed of both cellulose acetate rayon and viscose rayon and in which a selected diazoti'zable azobase acetate rayon black dyestuff and a selected diazotizable azo base viscose rayonblacx d-yestullare employed, and in which the pl-l of the coupling bath is maintained at 7 .0. during the operation of coupling the ditil) azonium salt of the d iazotizable azo base viscose rayon black dyestufi to the phloroglucinol, and in which the pH of the coupling bath is then lowered to and maintained at a point below 7.0 to enable the diazonium salt of the selected acetate rayon black dyestuff to be coupled to the phl'oroglucinol on the acid side.

5. The process defined in claim 1 in which the textile material is a so-called union, mixed, or combination fabric composed of both cellulose acetate rayonand cotton and inwhich a selected acetate rayon diazo-tizableazo base black dyestu-il and a selected di azotizable azo base black cotton dyestuif are employed, and in which the pH of the coupling bath is maintained at 7.0 during the operation of coupling the diazonium salt of the selected diazotizable azo base cotton black dyestufi to the phloroglucinol, and in which the pH of the coupling bath is then lowered to and maintained at a point below 7.0 to enable the diazonium salt of the selected diazotizable azo base acetate rayon black dyestufi to be coupled to the phloroglucinol on the acid side.

.6. The process defined in claim 1 in which the textile material is composed of nylon, and in which a selected diazotiZa-ble azobase nylon black dyestufi is employed therein, and in which the pH of the coupling bath is maintained between 5.0 and 7.0 to enable the diazonium salt of the selected diazotizable azo base nylon black dyestuff to couple to the phloroglucinol.

7'. The process defined in claim 1 in which textile material is a so-called mixed or combination fabric composed of both acetate rayon and wool and in which the pH of the coupling bath is maintained at about 6.5 to enable the chemotizable azo base black dyestuil to couple to the phloroglucinol on the acetate rayon component of the said mixed or union fabric during the coupling operation.

8. The process defined in claim 1 in which the textile material is a so-called mixed or combination fabric composed of both acetate rayon and silk and in which the pH of the coupling bath is maintained at about 6.5 to enable the diazotizable azo base black dyestuiif to couple to the phlcrroglucinolon the acetate rayon component of the saidmixed or union fabric during the coupling operation.

CHARLES E. MAHER.

REFERENCES @ITED The following references. are of record in the file of this patent:

UNITED' STATES PATENTS Number Name Date 1,022,408 Knoevenagel Sept. 5, 1911 2,102,789 Dreyfus Dec. 21, 1937 2,195,585 Seymour Apr. '2; 1940 2,196,984 Ellis Apr. 16, 1940 2,267,565 James Dec. 23, 1941 2,289,413 Ell-is July 14, 1942 2,403,900 Armour July 16, 1946 OTHER REFERENCES aromatic Diazo-Giompounds and Their Technical Applications, by H. Saunders, published in London by Edward Arnold 00., 1936, pages 104, 105. Available in Div. 63 ofPat. Off. 

1. A PROCESS FOR FORMING PERMANENT AND TRUE BLACK COLORS OR PIGMENTS, POSSESSING EXCELLENT WASH FASTNESS AND LIGHT FASTNESS, UPON HYDROPHOBIC TEXTILE MATERIALS, WHICH COMPRISES FORMING A COUPLING BATH CONTAINING PHOLOGLUCINOL (1,3,5-TRIHYDROXYBENZENE) AS THE COUPLING AGENT, DYEING THE HYDROPHOBIC, TEXTILE MATERIAL WITH A SELECTED DIAZOTIZABLE AZO BASE BLACK DYESTUFF PRESENT IN THE RATIO OF AT LEAST 3 MOLS OF THE BLACK DYESTUFF PER MOL OF PHLOROGLUCINOL, WORKING THE THUS DYED HYDROPHOBIC TEXTILE MATERIAL IN A DIAZOTIZING BATH TO FORM THE DIAZONIUM SALT OF THE SELECTED DIAZOTIZABLE AZO BASED BLACK DYESTUFF, ELIMINATING FROM THE COUPLING BATH PRIOR TO THE COUPLING OPERATION THEREIN ANY FREE NITROUS ACID WHICH MAY BE PRESENT IN THE COUPLING BATH, AND THEN WORKING THE THUS DYED AND DIAZOTIZED HYDROPHOBIC TEXTILE MATERIAL IN THE SAID COUPLING BATH TO COMPLETE THE COUPLING OPERATION THEREIN. 